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161.
A study was performed utilizing 3 mock eyes of different sizes to determine the precision and accuracy of 3 radiographic methods of localization of intraorbital foreign bodies. The Comberg method was found to be the most precise and accurate, next, the Sweet method, and then the modified spectacle frame method. However, the modified spectacle frame field expedient method of localization yielded a surprisingly high degree of accuracy in 2 of the 3 planes of reference, that is, mediolaterally and superointeriorly. A more accurate field expedient type of device which will permit greater accuracy in localization of intraorbital foreign bodies in the anteroposterior axis is currently under development. 相似文献
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The degeneration of the substantia nigra that characterises Parkinson's disease may cause an alteration in sensitivity of striatal dopamine receptors. The development of denervation supersensitivity has been held to be responsible for some of the effects of chronic levodopa therapy. The rotating rodent is an animal model commonly used to study the phenomenon of striatal dopamine receptor supersensitivity, and to investigate drugs which may prove to be beneficial in the treatment of Parkinson's disease. We have investigated as to whether long-term oral administration of levodopa to mice with unilateral destruction of striatal dopaminergic nerve terminals influences dopaminergic receptor denervation supersensitivity as judged by the circling response following systemically administered levodopa. It does not do so and the relevance of these findings to the treatment of Parkinson's disease is discussed. 相似文献
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BG Wallin G Sundl?f BM Eriksson P Dominiak H Grobecker LE Lindblad 《Canadian Metallurgical Quarterly》1981,111(1):69-73
Recordings of multiunit sympathetic activity were made in muscle branches of the peroneal nerve in 22 healthy subjects at rest in recumbent position. Nerve activity was quantitated in terms of burst incidence (number of pulse synchronous sympathetic bursts per 100 heart beats or per min). In a separate session, 4-45 months later, blood was drawn from an antecubital vein for noradrenaline analysis. Both sympathetic activity and plasma concentrations of noradrenaline varied widely between subjects and both parameters increased with age. There was a significant positive correlation between a subject's level of sympathetic activity and his plasma concentration of noradrenaline. It is suggested that overflow of transmitter from sympathetic terminals in muscles contributes significantly to plasma levels of noradrenaline at rest. 相似文献
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Karlov VI Padilla CE Soosaar K Matson LE Chun HM Webb GV 《Journal of the Optical Society of America. A, Optics, image science, and vision》2001,18(10):2565-2576
We present a new approach to processing of interferometric data, which dramatically improves operation on the smallest fraction of the fringe (approximately 1/1,000 of a wavelength and beyond). In particular, this approach, dubbed the variation-invariant subspace tracking approach (VISTA), makes it possible to operate a Michelson interferometer in a highly stable mode in which the estimation of optical path delay becomes invariant (insensitive) to a large class of systematic model errors. This previously unknown invariance property of interferometry follows from the fundamental odd-even symmetry of the channeled spectrum and its derivatives. VISTA offers a powerful algorithmic alternative for alleviating technological challenges in the design of high-precision long-baseline spaceborne interferometers. 相似文献
169.
Matson CL 《Applied optics》2001,40(31):5791-5801
The role that deconvolution plays in the achievable spatial resolution in optical diffusion tomography is examined for the case of imaging an inhomogeneity in an otherwise homogeneous medium. It is shown that, in the measured data, it is the shape of the turbid medium modulation transfer function that determines the maximum spatial resolution. When the turbid medium transfer function is deconvolved from the measured data, it is the signal-to-noise ratio properties of the Fourier-transformed measured data that determine the maximum spatial resolution. It is shown that deconvolution-based methods can improve the spatial resolution in measured data up to a factor of 5 for realistic noise levels. These results are demonstrated with computer-simulated data. 相似文献
170.